Compounds having one of the following formulae are disclosed:
wherein R1 and R2 are alkyl or aryl and R1 and R2 may be the same or different,
wherein R1 is alkyl or aryl, or
wherein alkyl is a linear or branched, saturated or unsaturated alkyl having C1-20 and wherein aryl is an aromatic ring having C6-15. Also methods of using the compounds, including methods of inhibiting an ethylene response in a plant.
1-Methylcyclopropene (1-MCP) is a cyclopropene derivative used as a synthetic plant growth regulator. It is structurally related to the natural plant hormone ethylene and is being used commercially to keep fruits, flowers or vegetables fresh, either by preventing or delaying the natural ripening process. It is also used to prevent premature wilting, leaf yellowing, premature opening of flowers as well as premature death (Chow, B., and P. McCourt, Genes Dev., 20 (15): 1998-2008 (2006); De Paepe, A., and D. Van der Straeten, Vitam, Horm., 72: 399-430 (2005)).
Ethylene is a plant hormone that exists as a gas and acts at trace levels throughout the life of a plant by stimulating or regulating various processes. There are three groups of compounds which bind to plant receptors. The first group that includes ethylene, carbon monoxide, acetylene or isocyanides, binds to the receptors and induce an ethylene response, such as the ripening of climacteric fruit, the opening of flowers and the shedding of leaves (Chow and McCourt 2006, DePaepe and Van der Straeten 2005). The second group containing olefins are weakly binding compounds that compete with ethylene for a receptor binding site and prevent it from inducing an ethylene response. They can only work if the ethylene level is relatively low. At high levels of ethylene, an ethylene response would still be observed because it will overrule the action of the inhibitor. The third group of compounds also interacts with the receptors and competes with ethylene for binding. However, in this case a single exposure of plant tissue to these compounds is enough to prevent ethylene from binding even at a very high level of ethylene, although this action disappears after several days either due to the diffusion of the compounds from the binding sites or the development of new receptors. 1-MCP is an important member of the third group. The tight binding characteristic of 1-MCP to the ethylene receptor in plants blocks the activities of ethylene (Serek, M., et al., Physiol. Plant.,94 (2): 229-232 (1995); Sisler, E. C., and M. Serek, Plant Biol., 5 (5): 473-480 (2003)).
Nationally, we dump $43 billion worth of food every year, most of which is composed of rotting fruits and vegetables. So it is of great importance to explore keeping fruits and vegetables fresh for a longer period of time. Cyclodextrin is being used as an encapsulating agent for 1-MCP to facilitate handling but it does not allow a controlled release of 1-MCP. Therefore, it can only be used in enclosed sites, such as coolers, truck trailers, greenhouses, storage facilities and shipping containers.
Thus there is a need for new compounds which will keep fruits and vegetables fresh for a longer period of time. Also needed are new compounds to be used in crop fields for the protection of crop yield from extreme weather conditions.